sound

• Sound waves

  • Created by vibrations
  • Move forwards and backwards
  • Compress and expand the medium
• Sound waves travel faster in liquids than gases
• Speed of Sound

  affected density and temperature of the medium
• The denser the medium


  The faster the sound
• The hotter the medium


  The slower the sound
• The speed of sound is around 340 m/s
• Hot

  Expand
• Cold

  Compress
• Pitch


  Determined by the frequency
• Ultrasound


  Sound above 20,000 Hz (above what humans can hear)
• Whales, bats, dolphins etc use ultrasound for echo location
• Ultrasound imaging


  Used to create images with sound, e.g. fetal scan, ocular scan (water)
• Sonar


  Scans that pass through and against dense objects
• Sonogram


  1. Properties (medical)

  2. Soft tissue (skin & blood vessels)

  3. Tissue (bones & muscle)

  4. Reflected against smooth solid surface

  5. Absorbed by soft surfaces
• Sound waves


  • Reflect as echo against smooth solid surface
  • Are absorbed by soft surfaces